1. Technical Field
The present invention relates to organic electroluminescent (EL) devices, methods for producing organic EL devices, and electronic apparatuses.
2. Related Art
Organic EL devices are self-luminous devices requiring no light source such as a backlight. An organic EL device includes light-emitting elements arranged on a substrate, each including a light-emitting layer formed of an organic EL material and held between a pair of electrodes. According to the direction in which light emitted from the light-emitting layer is output, organic EL devices can be classified into a bottom-emission structure, in which light is output through a substrate, or a top-emission structure, in which light is output through the opposite side.
In an organic EL device having the top-emission structure, the individual pixels are defined by partitions which partition pixel electrodes (first electrodes) to form substantially rectangular apertures. Of the pair of electrodes holding the light-emitting a layer, a common electrode (second electrode) is disposed on the side where light exits. The common electrode is formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).
An ITO or IZO film causes a voltage gradient inside the common electrode because the film has higher resistance than a metal film. This voltage imbalance inside the common electrode degrades the image quality of the organic EL device.
To avoid the voltage imbalance inside the common electrode, auxiliary lines having low resistance are disposed in contact with the common electrode on the partitions forming the individual pixels (for example see JP-A-2001-195008, JP-A-2003-288994, JP A-2004-207217, and JP-A-2005-235491). The auxiliary lines thus prevent the degradation of image quality of the organic EL device.
The organic EL device described above, however, has the following problem.
The organic EL device has an insufficient aperture rate per pixel because the auxiliary lines are formed on the partitions forming the pixel regions. The partitions must be formed so as to leave the regions required to form the apertures, the regions where the auxiliary lines are formed, and the regions required to provide a manufacturing margin for the auxiliary lines. This problem is more serious for organic EL devices having finer pixels.
Hence, the organic EL device requires more current to provide sufficient light intensity. This imposes a high load on, for example, the light-emitting layer, thus decreasing the life of the organic EL device.